The invention is based on a speed governor for fuel injection pumps of internal combustion engines.
From German Patent Application 36 41 794, a speed governor is already known in which a centrifugal adjuster converts an adjusting force, which corresponds to the rpm of the engine to be supplied, into an adjusting motion of a governor sleeve that via a governor lever connects the centrifugal adjuster to a fuel injection quantity adjusting device of a fuel injection pump. The flyweights act via bell cranks on the inner drag member part, which comprises a bolt and a drag spring acting axially upon it, the inner drag member part being guided in the governor sleeve which forms the outer drag member part; on the circumference of the governor sleeve, the governor lever engages an annular groove therein via a slide block.
The governor sleeve then performs not only the transmission of the adjusting motion from the centrifugal adjuster via the governor lever to the fuel injection quantity adjusting device but also performs an adaptation of the fuel supply quantity to the requirements of the engine to be supplied and stores the motion of the outer drag member part relative to the inner drag member part, such as it may occur for instance during engine braking.
During the adaptation process, in which the governor sleeve is displaced in the direction of the fuel injection pump counter to the drag spring, while the inner drag member part is stationary, a short spring travel with high resistance is necessary. Contrarily, upon a travel-storing motion, in which the governor sleeve maintains its position and the inner drag member part is displaced by the flyweights in the direction of the fuel injection pump, an escape function of the drag spring that receives the entire adjusting travel is necessary.
These mutually contradictory tasks are achieved in the known fuel injection pump with a bidirectionally acting drag spring, and in a second exemplary embodiment with two series-connected and each unidirectionally acting drag springs; the space in the governor sleeve puts limits on optimal spring design, so that to increase the spring storing travel during the escape function, an additional travel storing member is necessary, disposed on the governor mechanism.